Plasticization of resinous compositions



Patented Sept. 26, 1944 2,359,103 ICE PLASTICJZATION F RESINOUS COMPOSITION S Howard L. Gerhart and George E. Eilerman, Milwaukee, Wis.,assignors to Pittsburgh Plate Glass Company,

a corporation of Pennsylvania No Drawing. Application September 12,1941, Serial No. 410,602

6 Claims.

The present invention relates to resins of the type obtained byconjointly polymerizing an a p ethylenic dicarboxylic acid and apolymerizable vinyl compound,

One object of the invention is to provide a simple and economical methodof increasing the toughness and flexibility of resins of the foreo gtype.

It has heretofore been proposed to prepare artificial resins byconjointly polymerizing an ethylenic a ,6 dicarboxylic acid, such asmaleic acid, or fumaric acid and a vinylic compound, such as styrene.Generally the resultant products were white powdery substances whichwere soluble in dilute alkalies.

In Patent 2,230,240 and, also, in a copending application Serial No.242,127, filed November 23, 1938, to Howard L. Gerhart, are disclosedprocesses of conjointly polymerizing ethylenic a p dicarboxylic acids oranhydrides thereof and polymerizable olefins in such manner as to obtainclear, hard and strong resins ideally suited for use as embedmcnt mediafor specimens of various kinds, for molding to form objects, such ascostume jewelry and the like. These resins, according to the foregoingapplication, may be prepared by admixing the acid or anhydride, e. g.,maleic acid anhydride and the vinylic compound, e. g.,

styrene or other equivalents or by dissolving the components in a mutualsolvent such as triacetin. The reaction mixture is then subjected toactinic irradiation, preferably at a temperature within a range of about20 to 50 C. IAS a result of this treatment a polymerization will occurand usually within a period of about one hour a clear, hard resinousproduct, which is resistant to alkalies and solvents, will be obtained.If the reaction occurs in a solvent medium, such as triacetin, thelatter will be absorbed or taken up by the resin body.

Heretofore diificulty has been experienced in the plasticization of theresin compositions to obtain products of low shrinkage, a, maximumdegree of hardness, flexibility and toughness because very fewconventional plasticizers possess suflicient degree of solubility orcompatibility with the resin to be suitable for the p rp se.

The present invention is based upon the discovery that the nitroderivatives of alkanes, e. g., nitromethane, nitroethane, 1 or 2nitropropane, nitrobutane and the like compounds, are compatible with,and are excellent plasticizers for resins of the type of the copolymerof styrene and maleic anhydride. The plasticizers are normallyrelatively volatile compounds, but they may be employed as media forcopolymerization of styrene and maleic anhydride, and as a result of thereaction they are absorbed or taken up in the resultant resinous body.In the latter they are relatively permanently bound and do not evaporateeven after long exposure of the bodies in the open air.

The following comprise typical examples illustrating the preparation ofplasticized resin bodies by the method constituting the presentinvention:

Example 1 Parts Maleic anhydride 25 Styrene 31 Nitromethane 20 Dimethylphthalate or methyl levulinate 15 The mixture is heated with 0.1%benzoyl peroxide until it forms a light syrup. It is cooled to preventviolent boiling and poured into any desired mold. It will harden in aday to a clear transparent gummy plastic. This reaction can be hastenedby subjecting the syrup to actinic radiation; This plastic could behardened by baking it at a temperature below that of charring ordecomposing.

Example 2 Parts Maleic anhydride 25 Styrene 30 Nitromethane 1 30Subjected to the same treatment as in Example 1 or irradiated directlywithout preliminary heating to the sirupy state it forms a soft flexibleresin which is very tough and elastic.

The following compositions are all polymerized to a very hard, clear,strong transparent resin by the means already described in this and incopending applications:

Example 7 Hydroxy compounds are not plasticizers for these resins butwhen the hydroxy; compounds contain in addition the nitro grouping suchcom pounds become excellent plasticizing agents.

Grams Maleic anhydride 25 Styrene u 30 2-nitro-l-butanol 31 Example 8 1Grams Maleic anhydride 25 Styrene 32 2-nitro-2 methyl-l-propanol 20 Theesterification of the carboxyls of the ethylenic :13 dicarboxylic acidin Examples 1 to 8 is, also, contemplated as being within the purview ofthe invention. This may be accomplished by subjecting mixtures ofplasticizer, such as nitroethane, acid, such as maleic acid, vinyliccommay further be esterified with acids, such as stearic acid, oleicacid, free acids of linseed oil or tung oil, etc.

Further mixed esters may be prepared by esterifying a part of thecarboxyls by means of monohydroxy alcohol and the remainder with a di ortri hydroxy alcohol. Again the free hydroxyls of themixed esters may beesterified with mono carboxylic acids, such as those above enumerated.

The preparation of these various types of ester resins is discussed ingreater detail in an application for patent to Howard L. Gerhart andWilliam W. Bauer, Serial No. 323,945, filed March 14, 1940.

It will be apparent that the polymerizatlons may be conducted with thereactants in a suitable container or mold designed to impart a desiredshape or contour to the resultant bodies. The molds may be of glass orplastic designed to admit of irradiation of the reactants to speed uppolymerization. In some instances the molds may be open, or covered withtransparent coverings admitting of irradiation of an exposed surface ofthe contents. It will be apparent that the maleic anhydride and styrenemay also be partially polymerized in any convenient container and whilethe polymer is still sufficiently fluid it may be poured into a mold andthere subjected to further polymerization.

Partially polymerized mixtures in a fluid state may be brushed orsprayed upon surfaces of wood, stone, steel or the like and thenhardened by irradiation or baking to provide hard, durable coatings.

Objects, such as butterflies and insects in general, or objects of artand various types of specimens, may be embedded in the partiallypolymerized resin while the latter is fluid. Upon iurther polymerizingthe resin, specimens permain the hydrocarbon group, said nitroalkanebeing v imbibed in the resin.

nently embedded in a hard, transparent protective medium, are obtained.

In a further application of the invention solution of maleic anhydrideand styrene prepared in accordance with one of the preceding examples,e. g., Example 1, may be prepared and introduced betweentwo sheets ofglass. Upon irradiation of the sheets, polymerization of the reactantswill result and the sheets will be adhered or bonded together to providea safety glass of the type used in vehicles and the like.

In a still further application of the invention the hardened resin maybe polymerized to obtain a powder which can be molded under heat andpressure into bodies of any desired form.

The formation or resin'films, for example, by spreading the partiallypolymerized ingredients in a liquid state upon polished revolvingdrumsand there subjecting them to further hardening, is contemplated.These can be st ipp d from the It will be apparent that the resins afterthey have reached a solid state may be further hardened by subjectingthem to a baking operation at a temperature below that of decompositionor chairing.

The addition of pigments, such as titanium dioxide, zinc oxide, whitelead, lithopone or the like and coloring matters, such as organic dyes,is contemplated. These pigments may be used in amounts, for example, of5 to 70%, based on solids content. Wood flour or paper pulp may also beadded.

The forms of the invention herein described are to be considered merelyas being exemplary. It will be apparent to those skilled in the art thatnumerous modifications may be made therein without departure from thespirit of the invention or the scope of the appended claims,

What we claim is:

1. As a resinous composition a polymer of an ozfl unsaturated afidicarboxylic acid and styrene, which composition is permanentlyplasticized with a nitroalkane containing from 1 to 4 carbon atoms 2. Aprocess of forming a plasticized resin comprising copolymerizing maleicanhydride and styrene in solution in a nitroalkane containing from 1 to4 carbon atoms in the hydrocarbon group.

3. A process of forming a plasticized resin, which comprisescopolymerizing styrene and maleic anhydride in solution in nitroethane.

4. A process of preparing a plasticize d resin, which comprisescopolymerizing styrene and maleic anhydride in solution in a 1 hydroxy2- nitroalcohol containing 4 carbon atoms in the hydrocarbon group.

5. A process of forming a plasticized resin, which comprisescopolymerizing an afi unsaturated (1,8 dicarboxylic acid anhydride andstyrene in solution in a nitroalkane containing froml to 4 carbon atomsin the hydrocarbon group, said m'troalkane being adapted to be imbibedinto the resin to provide a permanent plasticizer,

in. A process of forming a plasticized resin comprising copolymerizingstyrene and maleic anhydride in solution in a compound selected from agroup consisting of nitroalkanes containing 1 to 4 carbon atoms in thehydrocarbon group and the hydroxy derivatives of said nitroalkanes.

HOWARD L. GERHART. GEORGE E. EILERMAN.

